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摘要
We investigated the influence of particle size on the microstructure and magnetocaloric effect of Fe-based alloy powders (11 mu m to 100 mu m in diameter). The degree of structure order varies with the powder size. The 11 mu m to 18 mu m powders show the largest peak magnetic entropy change (MEC). Increasing the degree of structure order tends to decrease the maximum MEC. Nevertheless, enhancement of refrigerant capacity and MEC (above 70 K) is achieved when the crystalline phase content is similar to 50% (above 75 mu m) in the 75 mu m to 100 mu m powders. Exponent n of the field dependence of MEC increases with the decrease in powder size above 22.5 K. The size dependence of the structure and properties is associated with the fact that a larger particle has a slower cooling rate and takes a longer time to form medium-to-long range ordered structures.
